Atomic-Scale Oxygen-Mediated Etching of 2D MoS<sub>2</sub> and MoTe<sub>2</sub>

Author(s): E. Harriet Ahlgren, Alexander Markevich, Sophie Scharinger, Bernhard Fickl, Georg Zagler, Felix Herterich, Niall McEvoy, Clemens Mangler, Jani Kotakoski
Abstract: Oxidation is the main cause of degradation of many 2D materials, including transition metal dichalcogenides (TMDs), under ambient conditions. Some of the materials are more affected by oxidation than others. To elucidate the oxidation-induced degradation mechanisms in TMDs, the chemical effects in single layer MoS₂ and MoTe₂ are studied in situ in an electron microscope under controlled low-pressure oxygen environments at room temperature. MoTe₂ is found to be reactive to oxygen, leading to significant degradation above a pressure of 1 × 10−7 torr. Curiously, the common hydrocarbon contamination found on practically all surfaces accelerates the damage rate significantly, by up to a factor of forty. In contrast to MoTe₂, MoS₂ is found to be inert under oxygen environment, with all observed structural changes being caused by electron irradiation only, leading to well-defined pores with high proportion of molybdenum nanowire-terminated edges. Using density functional theory calculations, a further atomic-scale mechanism leading to the observed oxygen-related degradation in MoTe₂ is proposed, and the role of the carbon in the etching is explored. Together, the results provide an important insight into the oxygen-related deterioration of 2D materials under ambient conditions relevant in many fields.
Organisation(s): Physics of Nanostructured Materials
External organisation(s): Trinity College Dublin
Journal: Advanced Materials Interfaces
Volume: 9
No. of pages: 9
ISSN: 2196-7350
DOI: https://doi.org/10.1002/admi.202200987
Publication date: 09-2022
Peer reviewed: Yes
Austrian Fields of Science 2012: 103042 Electron microscopy, 210004 Nanomaterials
Keywords
ASJC Scopus subject areas: Mechanics of Materials, Mechanical Engineering
Portal url: https://ucrisportal.univie.ac.at/en/publications/ff345830-2785-42e3-8d0f-ec7b22f5dd49